This invention relates generally to dispensers, and, more particularly to an aerosol dispenser assembly capable of controlled, low velocity dispersal of particulate aerosol materials by centrifugal force.
There are numerous fields in which it is desirable to dispense particulate aerosol materials into the atmosphere at a preselected time and place. For example, since the advent of radar, it has been known that small metallic particles dispensed in the atmosphere in a cloud are visible to radar detectors and tend to mask or obscure the presence of targets in or on the far side of the cloud. Such particles are generally placed in a dispenser and when airborn, at a preselected time, the dispenser is opened to discharge the deflecting material. A common technique for ejecting these particles is to place the material within a container and on top of a gas generating pyrotechnic. At the proper time the pyrotechnic is ignited and the gas generated thereby expels the particles from the container. While this appears to be a simple and technically feasible approach to the problem it has not worked satisfactorily. Gas generating dispensers are in many cases unreliable in operation and furthermore under some circumstances damage the particles themselves.
Also, in recent years the subject of radio propagation by scattering processes has become of great theoretical and practical importance. The discoveries that V.H.F., U.H.F., and S.H.F. signals are propagated to distances well beyond the horizon with losses much less than are predicted by diffraction theory and with high reliability have made possible the design of reliable point-to-point communication systems to operate over distances of 200 miles or more beyond the horizon. The systems employ high gain antennas, high power transmitters and space diversity reception. The cost of such equipment is justified in many applications because the need for intermediate repeater stations is obviated.
In beyond-the-horizon transmission, the reflective scattering of the electromagnetic wave depends upon the reflective characteristics of a natural layer of electrified particles found in the upper atmosphere. As is known, the characteristics of these layers vary and, hence, communication utilizing such layers tends to be erratic. Also, the signal-to-noise ratio of the overall communication system may vary and generally the ratio is lower than desirable even though communication is possible.
It is therefore desirable to create an artificial layer of electromagnetic wave reflective scattering material in a given zone of the upper atmosphere. An electromagnetic wave beam from a transmitter incident on the artificial layer at a given angle is caused to be reflectively scattered earthward toward a receiver spaced from said transmitter and adapted to receive the scattered electromagnetic energy of the beam.
Means to disperse the above reflecting material in the desired zone of the upper atmosphere included guns and the like, aircraft including guided missiles, ballons, rockets and the expelling of an ionized gas in the exhaust of such aircraft. Unfortunately, the prior art attempts at material scattering left much to be desired in reliability and reproducability.
A new area for the utilization of particle dispersement is in the field of optical communication in which these particles, sized to a particular wavelength of interest are dispersed into the exoatmosphere. The dispensing means in this field has generally taken the form of tubular or elliptical frangible glass vials to produce clouds of aerosols which would have a low growth rate. The vials were fractured at both ends by mechanical means in order to provide a linear dispersal of the particles. This technique, however, is unable to reproducibly create a cloud with low expansion velocity. Furthermore, the frangible glass vial, when broken, cannot reliably produce an aerosol cloud of known geometric shape or density.
Clearly a great need has arisen for a dispenser which is capable of reliably and reproducibly dispersing particulate aerosol materials into the atmosphere or above.